EFFECT OF LIGHT ON THE NUCLEOTIDE COMPOSITION OF TRANSFER RNAPHE OF WHEAT-GERM (TRITICUM-AESTIVUM)

The primary structure and minor nucleotide content of normally grown and etiolated wheat germ tRNAPhe were investigated. Etiolation was found to cause no alterations in the primary structure of the tRNAPhe but three minor nucleotides were missing. The minor nucleotides N2,N2-dimethylguanine (m22G), 7-methylguanine (m7G) and O2′-methylcytidine (Cm) present in the tRNAPhe of normally grown wheat germs could not be detected in that of etiolated ones. Their absence cannot be due to undermethylation because the same changes were identically located in the tRNAPhe molecule in a number of independent experiments. It is probably the result of a lack of light activation of the synthesis of some modifying enzymes via the phytochrome system. © 1979.